The periods of the earth's history in chronological order. Archean era

Is a collection of all forms of the earth's surface. They can be horizontal, inclined, convex, concave, complex.

The difference in height between the highest peak on land, Mount Chomolungma in the Himalayas (8848 m), and the Mariana Trench in the Pacific Ocean (11,022 m) is 19,870 m.

How was the relief of our planet formed? In the history of the Earth, there are two main stages of its formation:

• planetary(5.5-5.0 million years ago), which ended with the formation of the planet, the formation of the Earth's core and mantle;
• geological, which began 4.5 million years ago and continues to this day. It was at this stage that the formation of the earth's crust took place.

The source of information on the development of the Earth during the geological stage is primarily sedimentary rocks, which in the overwhelming majority were formed in the aquatic environment and therefore lie in layers. The deeper the layer lies from the earth's surface, the earlier it was formed and, therefore, is more ancient in relation to any layer that is closer to the surface and is younger. This simple reasoning underlies the concept relative age of rocks, which formed the basis for the construction geochronological table(Table 1).

The longest time intervals in geochronology are zones(from the Greek. aion - century, era). There are such zones as: cryptose(from the Greek. cryptos - hidden and zoe- life), covering the entire Precambrian, in the sediments of which there are no remains of skeletal fauna; phanerozoic(from the Greek. phaneros - explicit, zoe - life) - from the beginning of the Cambrian to our time, with a rich organic life, including skeletal fauna. The zones are not equal in terms of duration, so if the cryptosis lasted 3-5 billion years, then the phanerozoic lasted 0.57 billion years.

Table 1. Geochronological table

Zones are divided into era. Cryptozoic distinguishes Archean(from the Greek. archaios- the original, the most ancient, aion - century, era) and proterozoic(from the Greek. proteros - earlier, zoe - life) era; in the Phanerozoic - paleozoic(from the Greek. ancient and life), Mesozoic(from the Greek. tesos - medium, zoe - life) and Cenozoic(from the Greek. kainos - new, zoe - life).

Eras are divided into shorter periods of time - periods established only for the Phanerozoic (see Table 1).

The main stages of the development of the geographic envelope

The geographic envelope has come a long and difficult path of development. Three qualitatively different stages are distinguished in all development: prebiogenic, biogenic, anthropogenic.

Prebiogenic stage(4 billion - 570 million years) - the longest period. At this time, the process of increasing the thickness and complication of the composition of the earth's crust took place. By the end of the Archean (2.6 billion years ago), a continental crust with a thickness of about 30 km had already formed over vast areas, and in the Early Proterozoic, the separation of protoplatforms and protogeosynclines took place. During this period, the hydrosphere already existed, but the volume of water in it was less than it is now. Of the oceans (and then only by the end of the Early Proterozoic), one took shape. The water in it was salty and the salinity level was probably about the same as it is now. But, apparently, in the waters of the ancient ocean, the predominance of sodium over potassium was even greater than now, there were also more magnesium ions, which is associated with the composition of the primary earth's crust, the weathering products of which were carried into the ocean.

At this stage of development, the Earth's atmosphere contained very little oxygen, and there was no ozone shield.

Life most likely existed from the very beginning of this stage. According to indirect data, microorganisms already lived 3.8-3.9 billion years ago. The discovered remains of the simplest organisms are 3.5-3.6 billion years old. However, organic life from the moment of inception to the very end of the Proterozoic did not play a leading, decisive role in the development of the geographic envelope. In addition, many scientists deny the presence of organic life on land at this stage.

The evolution of organic life into the prebiogenic stage proceeded slowly, but nevertheless, 650-570 million years ago, life in the oceans was quite rich.

Biogenic stage(570 million - 40 thousand years) lasted during the Paleozoic, Mesozoic and almost the entire Cenozoic, with the exception of the last 40 thousand years.

The evolution of living organisms during the biogenic stage was not smooth: epochs of relatively calm evolution were replaced by periods of rapid and profound transformations, during which some forms of flora and fauna died out and others became widespread.

Simultaneously with the emergence of terrestrial living organisms, soils began to form in our modern understanding.

Anthropogenic stage began 40 thousand years ago and continues today. Although man as a biological genus appeared 2-3 million years ago, his impact on nature for a long time remained extremely limited. With the advent of Homo sapiens, this influence has increased significantly. It happened 38-40 thousand years ago. This is the starting point for the anthropogenic stage in the development of the geographic envelope.

Geological chronology, or geochronology, is based on elucidating the geological history of the most well-studied regions, for example, in Central and Eastern Europe. On the basis of broad generalizations, a comparison of the geological history of various regions of the Earth, the laws of the evolution of the organic world at the end of the last century, at the first International Geological Congresses, the International Geochronological Scale was developed and adopted, reflecting the sequence of time divisions during which certain complexes of deposits were formed, and the evolution of the organic world ... Thus, the international geochronological scale is a natural periodization of the history of the Earth.

Among the geochronological subdivisions stand out: eon, era, period, epoch, century, time. Each geochronological subdivision corresponds to a complex of deposits, distinguished in accordance with the change in the organic world and called stratigraphic: eonoteme, group, system, department, stage, zone. Consequently, a group is a stratigraphic unit, and the corresponding temporal geochronological unit represents an era. Therefore, there are two scales: geochronological and stratigraphic. The first is used when they talk about relative time in the history of the Earth, and the second when they are dealing with sediments, since some geological events took place in every place of the globe at any time. Another thing is that the accumulation of precipitation was not ubiquitous.

• The Archean and Proterozoic eonothems, covering almost 80% of the Earth's existence, are distinguished in cryptose, since the skeletal fauna is completely absent in the Precambrian formations and the paleontological method is not applicable to their dissection. Therefore, the division of the Precambrian formations is based primarily on general geological and radiometric data.
• The Phanerozoic eon covers only 570 Ma and the dissection of the corresponding eonothem of deposits is based on a wide variety of numerous skeletal fauna. The Phanerozoic eonothem is subdivided into three groups: Paleozoic, Mesozoic and Cenozoic, corresponding to major stages of the natural geological history of the Earth, the boundaries of which are marked by rather sharp changes in the organic world.

The names of eonothems and groups come from the Greek words:

• "archeos" - the most ancient, the most ancient;
• "proteros" - primary;
• "paleos" - ancient;
• "mezos" - medium;
• "kainos" is new.

The word "kryptos" means hidden, and "phanerozoic" means explicit, transparent, since the skeletal fauna appeared.
The word "zoi" comes from "zoikos" - vital. Therefore, the "Cenozoic era" means the era of new life, and so on.

Groups are subdivided into systems, the deposits of which were formed during one period and are characterized only by their inherent families or genera of organisms, and if they are plants, then by genera and species. Systems have been allocated in different regions and at different times, since 1822. Currently, 12 systems are distinguished, the names of most of which come from the places where they were first described. For example, the Jurassic system - from the Jurassic mountains in Switzerland, the Permian - from the Perm province in Russia, the Cretaceous - according to the most characteristic rocks - white writing chalk, etc. The Quaternary system is often called anthropogenic, since it is in this age interval that a person appears.

The systems are subdivided into two or three sections, which correspond to the early, middle, and late eras. The departments, in turn, are divided into tiers, which are characterized by the presence of certain genera and species of fossil fauna. And, finally, the stages are subdivided into zones that are the most fractional part of the international stratigraphic scale, which corresponds to time in the geochronological scale. The names of the tiers are usually given by the geographical names of the regions where this tier was identified; for example, the Aldanian, Bashkirian, Maastrichtian stages, etc. At the same time, the zone is designated by the most characteristic type of fossil fauna. The zone, as a rule, covers only a certain part of the region and is developed on a smaller area than the deposits of the stage.

All subdivisions of the stratigraphic scale correspond to the geological sections in which these subdivisions were first identified. Therefore, such sections are standard, typical and are called stratotypes, which contain only their characteristic complex of organic remains, which determines the stratigraphic volume of a given stratotype. Determination of the relative age of any layers consists in comparing the discovered complex of organic remains in the studied layers with the complex of fossils in the stratotype of the corresponding subdivision of the international geochronological scale, i.e. the age of the deposits is determined relative to the stratotype. That is why the paleontological method, despite its inherent shortcomings, remains the most important method for determining the geological age of rocks. Determination of the relative age, for example, of the Devonian deposits, indicates only that these deposits are younger than the Silurian, but older than the Carboniferous. However, it is impossible to establish the duration of the formation of Devonian deposits and to give a conclusion about when (in absolute chronology) the accumulation of these deposits took place. Only the methods of absolute geochronology are able to answer this question.

Tab. 1. Geochronological table

The problem of determining the absolute age of rocks, the duration of the existence of the Earth has long occupied the minds of geologists, and attempts to solve it have been made many times, for which various phenomena and processes were used. Early ideas about the absolute age of the Earth were curious. A contemporary of MV Lomonosov, the French naturalist Buffon, determined the age of our planet at only 74,800 years. Other scientists gave different figures, not exceeding 400-500 million years. It should be noted here that all these attempts were doomed to failure in advance, since they proceeded from the constancy of the rates of processes, which, as is known, changed in the geological history of the Earth. And only in the first half of the XX century. a real opportunity has appeared to measure the truly absolute age of rocks, geological processes and the Earth as a planet.

Life on Earth originated over 3.5 billion years ago, immediately after the completion of the formation of the earth's crust. Throughout the entire time, the emergence and development of living organisms influenced the formation of the relief, the climate. Also, tectonic and climatic changes that have occurred over the years have influenced the development of life on Earth.

The table of the development of life on Earth can be compiled based on the chronology of events. The entire history of the Earth can be divided into certain stages. The largest of them are the eras of life. They are divided into eras, eras - into periods, periods - into eras, epochs - into centuries.

Eras of life on Earth

The entire period of existence of life on Earth can be divided into 2 periods: Precambrian, or cryptose (primary period, 3.6 to 0.6 billion years), and Phanerozoic.

Cryptozoic includes the Archean (ancient life) and Proterozoic (primary life) eras.

Phanerozoic includes Paleozoic (ancient life), Mesozoic (middle life) and Cenozoic ( new life) era.

These 2 periods of the development of life are usually divided into smaller ones - eras. The boundaries between eras are global evolutionary events, extinctions. In turn, eras are divided into periods, periods - into eras. The history of the development of life on Earth is directly related to changes in the earth's crust and the planet's climate.

Eras of development, countdown

It is customary to allocate the most significant events in special time intervals - eras. Time is counted in reverse order, from the oldest life to the new. There are 5 eras:

Periods of development of life on Earth

The Paleozoic, Mesozoic and Cenozoic eras include periods of development. These are shorter periods of time compared to eras.

• Cambrian (Cambrian).
• Ordovician.
• Silurian (Silurian).
• Devonian (Devonian).
• Carboniferous (carbonaceous).
• Perm (Perm).

• Lower Tertiary (Paleogene).
• Upper Tertiary (Neogene).
• Quaternary, or anthropogen (human development).

The first 2 periods are included in the Tertiary period with a duration of 59 million years.

Proterozoic era (early life)

6. Perm (Perm)

2. Upper Tertiary (Neogene)

3. Quaternary or anthropogen (human development)

Development of living organisms

The table of the development of life on Earth assumes a division not only into time intervals, but also into certain stages of the formation of living organisms, possible climatic changes (ice age, global warming).

• Archean era. The most significant changes in the evolution of living organisms are the appearance of blue-green algae - prokaryotes, capable of reproduction and photosynthesis, the emergence of multicellular organisms. The appearance of living protein substances (heterotrophs) capable of absorbing organic substances dissolved in water. V further appearance these living organisms made it possible to divide the world into plant and animal.

• Mesozoic era.

• Triassic. Distribution of plants (gymnosperms). An increase in the number of reptiles. The first mammals, bony fish.
• Jurassic period. The predominance of gymnosperms, the emergence of angiosperms. The appearance of the first bird, the flowering of cephalopods.
• Cretaceous period. Distribution of angiosperms, reduction of other plant species. Development of bony fish, mammals and birds.

• Cenozoic era.
  • Lower Tertiary (Paleogene). The flowering of angiosperms. The development of insects and mammals, the appearance of lemurs, later primates.
  • Upper Tertiary (Neogene). Formation of modern plants. The appearance of the ancestors of people.
  • Quaternary period (anthropogen). Formation of modern plants, animals. The emergence of man.

Development of inanimate conditions, climate change

The table of the development of life on Earth cannot be presented without data on changes in inanimate nature. The emergence and development of life on Earth, new species of plants and animals, all this is accompanied by changes in inanimate nature and climate.

Climate change: the Archean era

The history of the development of life on Earth began through the stage of the predominance of land over water resources. The relief was poorly lined. The atmosphere is dominated by carbon dioxide, the amount of oxygen is minimal. Low salinity in shallow water.

The Archean era is characterized by volcanic eruptions, lightning, black clouds. The rocks are rich in graphite.

Climatic changes in the Proterozoic era

Land is a stone desert, all living organisms live in water. Oxygen accumulates in the atmosphere.

Climate Change: Paleozoic Era

During different periods of the Paleozoic era, the following climate changes took place:

• Cambrian period. The land is still deserted. The climate is hot.
• Ordovician period. The most significant changes are the flooding of almost all northern platforms.
• Silurian. Tectonic changes, conditions of inanimate nature are diverse. Mountain building takes place, the seas prevail over the land. Areas of different climates, including regions of cooling, have been determined.
• Devonian. The climate is dry and continental. Formation of intermontane depressions.
• Carboniferous period. Subsidence of continents, wetlands. Warm and humid climate, the atmosphere is rich in oxygen and carbon dioxide.
• Permian period. Hot climate, volcanic activity, mountain building, drying up of swamps.

In the Paleozoic era, mountains of the Caledonian folding were formed. Such changes in topography affected the world's oceans - sea basins have shrunk, and a significant land area has been formed.

The Paleozoic era marked the beginning of almost all major oil and coal deposits.

Climatic changes in the Mesozoic

The climate of different periods of the Mesozoic is characterized by the following features:

• Triassic. Volcanic activity, the climate is sharply continental, warm.
• Jurassic period. Mild and warm climate. Seas prevail over land.
• Cretaceous period. Retreat of the seas from land. The climate is warm, but at the end of the period, global warming is replaced by a cold snap.

In the Mesozoic era, previously formed mountain systems are destroyed, the plains go under water ( Western Siberia). In the second half of the era, the Cordillera, the mountains of Eastern Siberia, Indochina, partly Tibet were formed, the mountains of the Mesozoic folding were formed. A hot and humid climate prevails, favoring the formation of swamps and peat bogs.

Climate Change - Cenozoic Era

In the Cenozoic era, there was a general uplift of the Earth's surface. The climate has changed. Numerous glaciations of the earth's covers advancing from the north have changed the appearance of the continents of the Northern Hemisphere. Thanks to these changes, hilly plains were formed.

• Lower Tertiary period. Mild climate. Split by 3 climatic zones... Formation of continents.
• Upper Tertiary period. Dry climate. The emergence of steppes, savannas.
• Quaternary period. Multiple glaciation of the northern hemisphere. Cooling climate.

All changes during the development of life on Earth can be written in the form of a table, which will reflect the most significant stages in the formation and development modern world... Despite the already known research methods, and now scientists continue to study history, make new discoveries that allow modern society find out how life developed on Earth before the appearance of man.

Development of life on Earth lasts over 3 billion years. And this process continues to this day.

The first living things in the Archean were bacteria. Then came unicellular algae, animals and fungi. Unicellular organisms have been replaced by multicellular organisms. At the beginning of the Paleozoic, life was already very diverse: representatives of all types of invertebrates lived in the seas, the first land plants appeared on land. In the following eras, various groups of plants and animals formed and died out over many millions of years. Gradually, the living world became more and more similar to the modern one.

2.6. The history of the development of life

Previously, scientists believed that the living came from the living. Bacterial spores were brought in from space. Some bacteria created organic matter, others consumed and destroyed them. As a result, the most ancient ecosystem arose, the components of which were linked by the cycle of substances.

Modern scientists have proven that living things came from non-living nature. In the aquatic environment from inorganic substances under the influence of the energy of the Sun and the internal energy of the Earth, organic matter was formed. The most ancient organisms, bacteria, were formed from them.

In the history of the development of life on Earth, several eras are distinguished.

Archaea

The first organisms were prokaryotes. In the Archean era, a biosphere already existed, consisting mainly of prokaryotes. The very first living things on the planet are bacteria. Some of them were capable of photosynthesis. Photosynthesis was carried out by cyanobacteria (blue-green).

Proterozoic

As the oxygen content in the atmosphere increased, eukaryotic organisms began to appear. In the Proterozoic, unicellular plants arose in the aquatic environment, and then unicellular animals and fungi. An important event in the Proterozoic was the emergence of multicellular organisms. By the end of the Proterozoic, Various types invertebrates and chordates.

Paleozoic

Plants

Gradually, land appeared in place of the warm shallow seas. As a result, the first terrestrial plants originated from multicellular green algae. Forests arose in the second half of the Paleozoic. They consisted of ancient ferns, horsetails, and lyre, which multiplied by spores.

Animals

In the early Paleozoic, marine invertebrates flourished. In the seas, vertebrates - shell fish - developed and spread.

In the Paleozoic, the first terrestrial vertebrates appeared - the oldest amphibians. From them, at the end of the era, the first reptiles descended.

The most numerous in the seas of the Paleozoic (the era of ancient life) were trilobites - fossil arthropods, outwardly similar to giant woodlice. Trilobites - existed at the beginning of the Paleozoic, completely extinct 200 million years ago. They swam and crawled in shallow bays, feeding on plants and animal remains. There is an assumption that there were also predators among the trilobites.

Arachnids and giant flying insects, the ancestors of modern dragonflies, were the very first among animals to master the land. Their wingspan reached 1.5 m.

Mesozoic

In the Mesozoic, the climate became more arid. Ancient forests gradually disappeared. Spore-bearing plants were replaced by seed-propagating plants. Among animals, reptiles, including dinosaurs, flourished. At the end of the Mesozoic, many species of ancient seed plants and dinosaurs became extinct.

Animals

The largest of the dinosaurs were the brachiosaurs. They reached over 30 m in length and weighed 50 tons. These dinosaurs had a huge body, long tail and neck, small head. If they lived in our time, they would be higher than five-story buildings.

Plants

The most complex plants are flowering plants. They appeared in the middle of the Mesozoic (the era of middle life). Material from the site http://wikiwhat.ru

Cenozoic

Cenozoic - the heyday of birds, mammals, insects and flowering plants. Warm-bloodedness arose in birds and mammals due to the more perfect structure of organ systems. They have become less dependent on environmental conditions and have spread widely on Earth.

Geological time and methods of its determination

In the study of the Earth as a unique space object, the idea of ​​its evolution occupies a central place, therefore, an important quantitative-evolutionary parameter is geological time... The study of this time is engaged in a special science, which received the name Geochronology- geological chronology. Geochronology may be absolute and relative.

Remark 1

Absolute geochronology deals with determining the absolute age of rocks, which is expressed in units of time and, as a rule, in millions of years.

The determination of this age is based on the decay rate of isotopes of radioactive elements. This speed is a constant value from the intensity of physical and chemical processes does not depend. Age determination is based on methods of nuclear physics. Minerals containing radioactive elements, during the formation of crystal lattices, form closed system... In this system, the products of radioactive decay are accumulated. As a result, the age of the mineral can be determined if the rate of this process is known. The half-life of radium, for example, is $ 1590 years, and the complete decay of the element will occur in $ 10 times the half-life. Nuclear geochronology has its leading methods - lead, potassium-argon, rubidium-strontium and radiocarbon.

Nuclear geochronological methods have made it possible to determine the age of the planet, as well as the duration of eras and periods. Radiological time measurement proposed P. Curie and E. Rutherford at the beginning of the $ XX century.

Relative geochronology operates with such concepts as “early age, middle age, late”. There are several developed methods for determining the relative age of rocks. They come together in two groups - paleontological and non-paleontological.

The first play a major role due to their versatility and widespread use. The exception is the absence of organic remains in the rocks. With the help of paleontological methods, the remains of ancient extinct organisms are studied. Each layer of rocks is characterized by its own complex of organic residues. There will be more remains of highly organized plants and animals in each young layer. The higher the layer is, the younger it is. A similar pattern was established by an Englishman W. Smith... He owns the first geological map of England, on which rocks were divided by age.

Non-paleontological methods determination of the relative age of rocks are used in cases where organic remains are absent. More effective then will be stratigraphic, lithological, tectonic, geophysical methods... With the help of the stratigraphic method, it is possible to determine the sequence of the bedding of layers at their normal occurrence, i.e. the underlying layers will be more ancient.

Remark 3

The sequence of rock formation determines relative geochronology, and their age in units of time is already determined absolute geochronology. Task geological time is to determine the chronological sequence of geological events.

Geochronological table

Scientists use various methods to determine the age of rocks and to study them, and for this purpose a special scale was drawn up. Geological time on this scale is divided into time intervals, each of which corresponds to a certain stage in the formation of the earth's crust and the development of living organisms. The scale was named geochronological table, in which the following divisions are distinguished: eon, era, period, era, century, time... Each geochronological subdivision is characterized by its own complex of deposits, which is called stratigraphic: eonoteme, group, system, department, tier, zone... A group, for example, is a stratigraphic unit, and a temporary geochronological unit corresponding to it represents era. Based on this, there are two scales - stratigraphic and geochronological... The first scale is used when it comes to sediments, because in any period of time some geological events took place on the Earth. The second scale is needed to determine relative time... Since its adoption, the content of the scale has changed and improved.

The largest stratigraphic subdivisions at present are eonotems - Archean, Proterozoic, Phanerozoic... In the geochronological scale, they correspond to zones of different duration. By the time of existence on Earth, they stand out Archean and Proterozoic eonothems covering almost $ 80% of the time. Phanerozoic eon the time is much shorter than the previous eons and covers only $ 570 million years. This ionotheme is divided into three main groups - Paleozoic, Mesozoic, Cenozoic.

The names of the eonothems and groups are of Greek origin:

• Archeos means most ancient;
• Proteros is primary;
• Paleos is ancient;
• Mesos - medium;
• Kainos is new.

From the word “ zoiko with ", which means vital, the word" zoey". Based on this, eras of life on the planet are distinguished, for example, the Mesozoic era means the era of average life.

Eras and periods

According to the geochronological table, the history of the Earth is divided into five geological eras: Archean, Proterozoic, Paleozoic, Mesozoic, Cenozoic... In turn, the eras are subdivided into periods... There are much more of them - $ 12. The length of the periods varies from $ 20 - $ 100 million years. The last one indicates its incompleteness. Quaternary Cenozoic, its duration is only $ 1.8 million years.

Archean era. This time began after the formation of the earth's crust on the planet. By this time, there were mountains on Earth and the processes of erosion and sedimentation began to take effect. Archaea lasted approximately $ 2 billion years. This era is the longest in duration, during which volcanic activity was widespread on Earth, there were deep uplifts, which resulted in the formation of mountains. Most of the fossils are under the influence high temperature, pressure, mass movement, was destroyed, but little data about that time have survived. In the rocks of the Archean era, pure carbon is found in dispersed form. Scientists believe that these are altered remains of animals and plants. If the amount of graphite reflects the amount of living matter, then there was a lot of it in the Archean.

Proterozoic era... In terms of duration, this is the second era, spanning $ 1 billion years. During the era, there was a large amount of sediment deposition and one significant glaciation. Ice sheets spread from the equator to $ 20 $ degrees of latitude. Fossils found in the rocks of this time are evidence of the existence of life and its evolutionary development. Sponge spicules, remains of jellyfish, fungi, algae, arthropods, etc. were found in the Proterozoic sediments.

Palaeozoic... In this era stands out six periods:

• Cambrian;
• Ordovician,
• Silurian;
• Devonian;
• Carbon or coal;
• Perm or Perm.

The duration of the Paleozoic is $ 370 million years. During this time, representatives of all types and classes of animals appeared. Only birds and mammals were missing.

Mesozoic era... The era is divided into three period:

• Triassic;

The era began about $ 230 million years ago and lasted $ 167 million years. During the first two periods - Triassic and Jurassic- most of the mainland areas rose above sea level. The Triassic climate is dry and warm, and in the Jurassic it became even warmer, but was already humid. In the state Arizona there is a famous stone forest that exists since Triassic period. True, only trunks, logs and stumps remained from the once mighty trees. At the end of the Mesozoic era, or rather in the Cretaceous period, a gradual advance of the sea takes place on the continents. The North American continent at the end of the Cretaceous period experienced submersion and as a result the waters of the Gulf of Mexico merged with the waters of the Arctic basin. The mainland was divided into two parts. The end of the Cretaceous period is characterized by a large uplift, called alpine mountain building... At this time, the Rocky Mountains, Alps, Himalayas, Andes appeared. Intense volcanic activity began in the west of North America.

Cenozoic era... This is a new era that has not yet ended and continues at the present time.

The era was divided into three periods:

• Paleogene;
• Neogene;
• Quaternary.

Quaternary the period has a number of unique features. This is the time of the final formation of the modern face of the Earth and the ice ages. New Guinea and Australia became independent, moving closer to Asia. Antarctica remained where it was. Two Americas have connected. Of the three periods of the era, the most interesting is quaternary period or anthropogenic... It continues today, and was allocated in $ 1829 by a Belgian geologist J. Denoyer... Cold snaps change with warming, but its most important feature is human appearance.

Modern man lives in the Quaternary period of the Cenozoic era.

The idea of how life was born in the ancient eras of the Earth give us fossil remains of organisms, but they are distributed among individual geological periods extremely uneven.

Geological periods

The era of the ancient life of the Earth includes 3 stages of the evolution of the plant and animal world.

Archean era

Archean era- the oldest era in the history of existence. Its origin dates back to about 4 billion years ago. And the duration is 1 billion years. This is the beginning of the formation of the earth's crust as a result of the activity of volcanoes and air masses, abrupt changes in temperature and pressure. There is a process of destruction of primary mountains and the formation of sedimentary rocks.

The most ancient Archaeozoic layers of the earth's crust are represented by highly altered, otherwise metamorphosed rocks, therefore they do not contain noticeable remains of organisms.
But it is completely wrong on this basis to consider the Archaeozoic as a lifeless era: in the Archaeozoic there were not only bacteria and algae, but also more complex organisms.

Proterozoic era

The first reliable traces of life in the form of extremely rare finds and poor-quality preservation are found in proterozoic, otherwise - the era of "primary life". The duration of the Proterozoic era is about 2 million years.

Traces of crawling found in the rocks of the Proterozoic annelids, sponge needles, shells of the simplest forms of brachiopods, arthropod remains.

Shoulder-footed, distinguished by an exceptional variety of forms, were widespread in the ancient seas. They are found in sediments of many periods, especially the next, Paleozoic era.

Brachiopod shell "Horistites Moskvenzis" (ventral valve)

Only certain types brachiopods. Most of the brachiopods had a shell with unequal valves: the abdominal, on which they lie or are attached to the seabed with the help of a "leg", was usually larger than the dorsal. On this basis, in general, it is not difficult to recognize brachiopods.

The insignificant amount of fossil remains in Proterozoic sediments is explained by the destruction of most of them as a result of alteration (metamorphization) of the containing rock.

Sediments help to judge how much life was represented in the Proterozoic. limestone which then turned into marble... Limestones apparently owe their origin to a special type of bacteria that secreted carbonic lime.

The presence of interlayers in the Proterozoic sediments of Karelia shungite, similar to anthracite coal, suggests that the initial material for its formation was the accumulation of algae and other organic residues.

In this distant time, the most ancient land was still not lifeless. Bacteria settled in the vast expanses of the still deserted primary continents. With the participation of these simplest organisms, the weathering and loosening of the rocks that formed the most ancient earth's crust took place.

According to the assumption of the Russian academician L. S. Berga(1876-1950), who studied how life arose in the ancient eras of the Earth, at this time soils had already begun to form - the basis further development vegetation cover.

Palaeozoic

Deposits next in time Paleozoic era, in other words, the era of "ancient life", which began about 600 million years ago, sharply differ from the Proterozoic in the abundance and variety of forms even in the most ancient, Cambrian period.

Based on the study of the remains of organisms, it is possible to reconstruct the following picture of the development of the organic world, characteristic of this era.

There are six periods of the Paleozoic era:

Cambrian period

Cambrian period was described for the first time in England, the Cambrian county, from where its name came. During this period, all life was associated with water. These are red and blue-green algae, limestone algae. Algae released free oxygen, which enabled the development of organisms that consume it.

A close look at the blue-green Cambrian clays, which are clearly visible in deep sections of river valleys near St. Petersburg and especially in the coastal regions of Estonia, made it possible to establish in them (through a microscope) the presence of plant spores.

This definitely suggests that some species that have existed in water bodies since the earliest times of the development of life on our planet moved to land about 500 million years ago.

Among the organisms that inhabited the most ancient Cambrian reservoirs, invertebrates enjoyed exceptional distribution. Invertebrates, except for the smallest protozoa - rhizopods, were widely represented worms, brachiopods and arthropods.

Among arthropods, these are primarily various insects, especially butterflies, beetles, flies, dragonflies. They appear much later. In addition to insects, this type of animal world also includes arachnids and centipedes.

Among the oldest arthropods, there were especially many trilobites, similar to modern woodlice, only much larger than them (up to 70 centimeters), and crustaceans, sometimes reaching impressive sizes.

In the body of a trilobite, three lobes are clearly distinguished, and it is not without reason that it is called that: in translation from the ancient Greek "trilobos" - three-lobe. Trilobites not only crawled along the bottom and buried themselves in the silt, but could also swim.

Among trilobites, generally medium-sized forms prevailed.
By the definition of geologists, trilobites - "guiding fossils" - are characteristic of many deposits of the Paleozoic.

Fossils that are dominant at a given geological time are called guiding fossils. The leading fossils are usually easily dated by the age of the deposits in which they are found. Trilobites flourished in the Ordovician and Silurian periods. They disappeared at the end of the Paleozoic era.

Ordovician period

Ordovician period characterized by a warmer and milder climate, as evidenced by the presence of limestone, shale and sandstone in the rock sediments. At this time, the area of ​​the seas increases significantly.

This promotes the reproduction of large trilobites, 50 to 70 cm long. In the seas appear sea ​​sponges, molluscs, and the first corals.

Silurian

What did the Earth look like in Silurian? What changes have occurred on the pristine continents? Judging by the imprints on clay and other stone material, we can definitely say that at the end of the period the first terrestrial vegetation appeared on the shores of water bodies.

The first plants of the Silurian period

They were small leafy plants, resembling rather sea brown algae, which have neither roots nor leaves. The role of leaves was played by green, sequentially branching stems.

The scientific name of these ancient progenitors of all terrestrial plants (psilophytes, otherwise - "naked plants", that is, plants without leaves) well conveys their distinctive features. (Translated from the ancient Greek "psilos" is bald, naked, and "phytos" is a trunk). Their roots were also undeveloped. Psilophytes grew on swampy swampy soils. Imprint in breed (right) and regenerated plant (left).

Inhabitants of reservoirs of the Silurian period

From inhabitants marine Silurian reservoirs it should be noted, apart from trilobites, coral and echinoderms - sea ​​lilies, sea urchins and stars.

The sea lilies, the remains of which were found in the sediments, looked very little like carnivorous animals. The sea lily "Acantocrinus-rex" means "prickly lily-king" in translation. The first word is formed from two Greek words: "acanthus" - a thorny plant and "crinon" - a lily, the second Latin word "rex" - a king.

A huge number of species were represented by cephalopods, and especially brachiopods. In addition to cephalopods, which had an inner shell, like belemnites, cephalopods with an external shell were widespread in the earliest periods of the life of the Earth.

The shell was straight and bent in a spiral shape. The shell was sequentially divided into chambers. In the largest, outer chamber, the body of a mollusk was placed, the rest were filled with gas. A tube passed through the chambers - a siphon, which allowed the mollusk to regulate the amount of gas and, depending on this, float or sink to the bottom of the reservoir.

At present, of such cephalopods, only one boat with a coiled shell has been preserved. Ship, or nautilus, which is the same thing, translated from Latin - an inhabitant of the warm sea.

The shells of some Silurian cephalopods, such as orthoceras (translated from the ancient Greek "straight horn": from the words "ortoe" - straight and "keras" - horn), reached gigantic proportions and looked more like a straight two-meter pillar than a horn.

Limestones in which orthoceratites are found are called orthoceratite limestones. Square limestone slabs were widely used in pre-revolutionary St. Petersburg for sidewalks, and characteristic cuts of orthoceratite shells were often clearly visible on them.

A remarkable event of the Silurian time was the appearance of clumsy “ shell fish”, Which had an external bone shell and not ossified internal skeleton.

Their spinal column was answered by a cartilaginous cord - a chord. The carapaces did not have jaws or paired fins. They were poor swimmers and therefore stuck more to the bottom; silt and small organisms served as food.

The carapace fish pterichtis was generally a poor swimmer and led a natural lifestyle.

It can be assumed that Botryolepis was already much more mobile than pterychtis.

Silurian marine predators

In later sediments, there are already remnants of marine predators close to sharks. From these lower fish, which also possessed a cartilaginous skeleton, only teeth were preserved. Judging by the size of the teeth, for example, from the deposits of the Carboniferous age of the Moscow region, it can be concluded that these predators reached significant sizes.

In the development of the animal world of our planet, the Silurian period is interesting not only because the distant ancestors of fish appear in its reservoirs. At the same time, another equally important event took place: representatives of arachnids got out of the water onto land, among them were ancient scorpions, still very close to crustaceans.

On the right, at the top - a predator - pterygotus, armed with strange claws, reaching 3 meters, glory - eurypterus - up to 1 meter long.

Devonian

The dry land - the arena of the future life - gradually takes on new features, especially characteristic of the next, the Devonian period. At this time, woody vegetation already appears, first in the form of undersized shrubs and small trees, and then larger ones. Among the Devonian vegetation, we will meet well-known ferns, other plants will remind us of the graceful herringbone of horsetail and green ropes of lymphoids, only not creeping along the ground, but proudly rising upward.

In the later in age Devonian deposits, fern-like plants also appear, which multiplied not by spores, but by seeds. These are seed ferns, which occupy a transitional position between spore and seed plants.

Fauna of the Devonian period

Animal world seas Devonian period rich in brachiopods, corals and sea lilies; trilobites are beginning to play a secondary role.

Among the cephalopods, new forms appear, only not with a straight shell, like in Orthoceras, but with a spirally twisted one. They are called ammonites. They got their name from the Egyptian sun god Ammon, near the ruins of a temple in Libya (in Africa), these characteristic fossils were first discovered.

By their general appearance, it is difficult to confuse them with other fossils, but at the same time, it is necessary to warn young geologists about how difficult it is to identify individual types of ammonites, the total number of which is not hundreds, but thousands.

Ammonites flourished especially in the next, Mesozoic era. .

Fish developed significantly in the Devonian period. In armored fish, the bony carapace was shortened, which made them more mobile.

Some armored fish, such as the nine-meter giant dinichtis, were terrible predators (in Greek, "deinos" - terrible, terrible, and "ichthis" - fish).

The nine-meter dinichthis was obviously a great threat to the inhabitants of the reservoirs.

In the Devonian reservoirs, there were also cross-finned fish, from which lungfish came from. This name is explained by the structural features of the paired fins: they are narrow and, moreover, sit on an axis covered with scales. This feature differs, for example, from pikeperch, perch and other bony fish called ray-finned.

Cisfeathers are the ancestors of teleost fishes, which appeared much later - at the end of the Triassic.
We would not have had an idea of ​​what exactly the cross-finned fish looked like, which lived at least 300 million years ago, if it were not for the successful catches in the middle of the twentieth century off the coast South Africa the rarest specimens of their modern generation.

They live, obviously, at considerable depths, which is why they come across so rarely to fishermen. The captured species was named coelacanth. It reached 1.5 meters in length.
By their organization, lungfish are close to the cross-finned fish. They have lungs that match the swim bladder of a fish.

By their organization, lungfishes are close to cross-finned fishes. They have lungs that match the swim bladder of a fish.

How unusual the cross-finned looked can be judged by the specimen, the coelacanth caught in 1952 near the Comoros, west of the island of Madagascar. This 1.5 liter fish weighed about 50 kg.

The descendant of ancient lung-breathing fish - the Australian ceratodus (translated from ancient Greek - horntooth) - reaches two meters. He lives in drying up reservoirs and, while there is water in them, breathes with gills, like all fish, when the reservoir begins to dry out, he switches to pulmonary respiration.

His respiratory organs are the swim bladder, which has a cellular structure and is equipped with numerous blood vessels. In addition to ceratodus, two more species of lungfish are now known. One of them lives in Africa, and the other in South America.

Transition of vertebrates from water to land

Amphibian transformation table.

The first picture shows the oldest cartilaginous fish, diplocanthus (1). Under it is a primitive cross-finned eustenopteron (2), below is a supposed transitional form (3). In a huge amphibian eogirinus (about 4.5 m in length), the limbs are still very weak (4), and only as they master the terrestrial lifestyle, they become a reliable support, for example, for a heavy Eriops, about 1.5 m in length (5).

This table helps to understand how, as a result of a gradual change in the organs of movement (and respiration), aquatic organisms moved to land, how the fin of a fish was transformed into a limb of amphibians (4), and then reptiles (5). Along with this, the spine and skull of the animal changes.

The first wingless insects and terrestrial vertebrates appeared in the Devonian period. Hence, it can be assumed that it was at this time, and perhaps even somewhat earlier, that the transition of vertebrates from water to land took place.

It was realized through such fish, in which the swim bladder was changed, like in lungs, and limbs, similar to fins, gradually turned into five-toed ones, adapted to a terrestrial lifestyle.

Metopoposaurus was still struggling to get out onto land.

Therefore, the closest ancestors of the first terrestrial animals should be considered not lung-breathing, but precisely cross-finned fishes, adapted to breathing atmospheric air as a result of periodic drying out of tropical reservoirs.

The connecting link of terrestrial vertebrates with cross-finned are ancient amphibians, or amphibians, united by the common name of stegocephaly. Translated from the ancient Greek stegocephaly - "covered head": from the words "stege" - a roof and "mullet" - a head. This name is given because the roof of the skull is a solid shell of closely adjacent bones.

There are five openings in the skull of a stegocephalus: two pairs of openings — the eye and nasal ones, and one — for the parietal eye. By appearance stegocephals somewhat resembled salamanders and often reached considerable sizes. They lived in swampy areas.

The remains of stegocephals were sometimes found in the hollows of tree trunks, where they were obviously sheltered from daylight. In the larval state, they breathed with gills, like modern amphibians.

Stegocephalus found especially favorable conditions for their development in the next Carboniferous period.

Carboniferous period

Warm and humid climate, especially the first half Carboniferous period, favored the lush flowering of terrestrial vegetation. Coal forests never seen before, of course, were completely different from modern ones.

Among those plants that about 275 million years ago settled in the marshy swampy expanses, they clearly stood out in their characteristic features giant treelike horsetails and lymphoids.

Of the treelike horsetails, the calamites used a significant distribution, and from the ploons - the giant lepidodendrons and the graceful sigillaria somewhat inferior to them in size.

In the seams of coal and the rocks that cover them, well-preserved remains of vegetation are often found, not only in the form of clear imprints of leaves and tree bark, but also whole stumps with roots and huge trunks that have turned into coal.

From these fossil remains, you can not only restore the general appearance of the plant, but also get acquainted with its internal structure, which is clearly visible under a microscope in thin sections of the trunk, as thin as a sheet of paper. The Kalamites derive their name from the Latin word "kalamus" - reed, reed.

Slender, hollow inside calamite trunks, ribbed and with transverse constrictions, as in the well-known horsetails, rose in slender columns 20-30 meters from the ground.

Small narrow leaves, collected by rosettes on short stalks, gave, perhaps, some resemblance to Kalamite with the Siberian taiga larch, transparent in its elegant headdress.

Nowadays, horsetails - field and forest - are common throughout the globe, except for Australia. In comparison with their distant ancestors, they seem to be pathetic dwarfs, who, moreover, especially field horsetail, enjoy a bad reputation with the farmer.

Horsetail is the worst weed, which is difficult to fight, since its rhizome goes deep into the ground and constantly gives new shoots.

Large species of horsetails - up to 10 meters in height are currently preserved only in tropical forests South America... However, these giants can only grow leaning against neighboring trees, since they are only 2-3 centimeters across.
Lepidodendrons and sigillaria occupied a prominent place among the Carboniferous vegetation.

Although in appearance they did not look like modern lyres, they nevertheless resembled them in one characteristic feature. The powerful trunks of lepidodendrons, reaching 40 meters in height, with a diameter of up to two meters, were covered with a distinct pattern of fallen leaves.

These leaves, while the plant was still young, sat on the trunk in the same way as its small green scales - leaves - sit on the plow. As the tree grew, the leaves grew old and fell off. From these scaly leaves the giants of the Carboniferous forests got their name - lepidodendrons, otherwise - "scaly trees" (from the Greek words: "lepis" - scales and "dendron" - a tree).

Traces of fallen leaves on the bark of sigillaria had a slightly different shape. They differed from lepidodendrons in their lower height and greater slenderness of the trunk, which branched only at the very top and ended in two huge bunches of hard leaves one meter each.

Acquaintance with the carboniferous vegetation will be incomplete, if not to mention also the kordaites, which are close to conifers in the structure of their wood. They were tall (up to 30 meters), but relatively thin-stemmed trees.

The Cordaites derive their name from the Latin elephant "kor" - heart, since the seed of the plant had a heart-shaped shape. These beautiful trees crowned with a lush crown of ribbon-like leaves (up to 1 meter in length).

Judging by the structure of the wood, the trunks of the coal giants still did not have the strength that is inherent in the bulk modern trees... Their bark was much stronger than wood, hence the general fragility of the plant, weak resistance to fracture.

Strong winds and especially storms broke trees, felled huge forests, and new lush shoots grew out of the swampy soil again ... The dumped wood served as the initial material from which powerful coal seams were later formed.

Lepidodendrons, otherwise - scaly trees, reached enormous sizes.

It is not correct to attribute the formation of coal only to the Carboniferous period, since coals are also found in other geological systems.

For example, the oldest Donetsk coal basin was formed in the Carboniferous time. The Karaganda basin is the same age as it.

As for the largest Kuznetsk basin, it only in its insignificant part belongs to the Carboniferous system, and mainly to the Permian and Jurassic systems.

One of the largest pools - "Zapolyarnaya Kochegarka" - the richest Pechora basin, was also formed mainly in the Permian time and in a smaller part - in the Carboniferous.

Flora and fauna of the Carboniferous period

For marine sediments Carboniferous period representatives of the simplest animals from the class are especially characteristic rhizome... The most typical were the fusulins (from the Latin word "fuzus" - "spindle") and schwagerins, which served as the source material for the formation of strata of fusulin and schwagerin limestones.

Carboniferous rhizomes - fusulin (1) and schwagerin (2) are increased 16 times.

Oblong, like wheat grains, fusulins and almost spherical schwagerins are clearly visible on the limestones of the same name. Corals and brachiopods developed magnificently, giving many leading forms.

The most widespread were the genus Produktus (translated from Latin - "stretched") and Spirifer (translated from the same language - "bearing spiral", which supported the soft "legs" of the animal).

Trilobites, which prevailed in previous periods, are much less common, but on land other representatives of arthropods begin to gain a noticeable distribution - long-legged spiders, scorpions, huge centipedes (up to 75 centimeters in length) and especially giant insects, similar to dragonflies, with a wingspan up to 75 centimeters! The largest modern butterflies in New Guinea and Australia reach a wingspan of 26 centimeters.

The oldest Carboniferous dragonfly seems to be an exorbitant giant in comparison with the modern one.

Judging by the fossil remains, sharks have noticeably multiplied in the seas.
Amphibians, firmly entrenched on land in the Carboniferous, go through a further path of development. The dryness of the climate, which increased at the end of the Carboniferous period, gradually forces the ancient amphibians to move away from the aquatic way of life and move mainly to terrestrial existence.

These organisms, transitional to a new way of life, laid eggs on land, and did not spawn into the water, like amphibians. The offspring hatched from eggs acquired such characteristics that sharply distinguished them from their progenitors.

The body was covered, like a shell, with scale-like outgrowths of the skin, which protected the body from moisture loss through evaporation. So reptiles, or reptiles, separated from amphibians (amphibians). In the next, Mesozoic era, they conquered land, water and air.

Permian period

The last period of the Paleozoic - Permian- was much shorter in duration than the coal one. It should be noted, in addition, the great changes that took place in the ancient geographic map world - land, as confirmed by geological research, gains a significant predominance over the sea.

Permian plants

The climate of the northern continents of the Upper Permian was dry and sharply continental. Sandy deserts are widely spread in places, as evidenced by the composition and reddish tint of the rocks that make up the Permian Formation.

This time was marked by the gradual extinction of the giants of the Carboniferous forests, the development of plants close to conifers, and the appearance of cycads and ginkgoids, which became widespread in the Mesozoic.

Cycad plants have a spherical and tuberous stem immersed in the soil, or, conversely, a powerful columnar trunk up to 20 meters high, with a lush rosette of large feathery leaves. In appearance, cycad plants resemble the modern sago palm of the tropical forests in the Old and New Worlds.

Sometimes they form impassable thickets, especially on the flooded banks of the rivers of New Guinea and the Malay Archipelago (Great Sunda Islands, Small Sunda, Moluccas and Philippines). Nutritious flour and cereal (sago) are made from the soft heart of the palm tree, which contains starch.

Sago bread and porridge are the daily food of millions of inhabitants of the Malay Archipelago. The sago palm is widely used in housing and household products.

Another very peculiar plant, ginkgo, is also interesting because it has survived in the wild only in some places in southern China. Since time immemorial, Ginkgo has been carefully bred near Buddhist temples.

Ginkgo was brought to Europe in the middle of the 18th century. Now it is found in park culture in many places, including ours on the Black Sea coast. Ginkgo is a large tree up to 30-40 meters in height and up to two meters thick, in general resembles a poplar, and in youth it looks more like some conifers.

Leaves are petiolate, like that of an aspen, have a fan-shaped blade with fan-shaped venation without transverse bridges and an incision in the middle. For the winter, the foliage falls. The fruit - a fragrant drupe like a cherry - is as edible as the seeds. In Europe and Siberia, ginkgo disappeared during the Ice Age.

Cordaites, conifers, cycads and ginkgoes belong to the group of gymnosperms (since their seeds lie open).

Angiosperms, monocotyledonous and dicotyledonous, appear somewhat later.

Fauna of the Permian period

Among the aquatic organisms that inhabited the Permian seas, ammonites were prominently distinguished. Many groups of marine invertebrates, such as trilobites, some corals and most brachiopods, have become extinct.

Permian period characterized by the development of reptiles. Particularly noteworthy are the so-called animal-like lizards. Although they possessed some features characteristic of mammals, for example, teeth and skeletal features, they nevertheless retained a primitive structure that brings them closer to stegocephals (from which reptiles originated).

The bestial Permian lizards were of considerable size. The sedentary herbivorous pareiasaurus reached two and a half meters in length, and the formidable predator with the teeth of a tiger, in other words, the "animal-toothed lizard" - foreigners, was even larger - about three meters.

Pareiasaurus in translation from ancient Greek means "chubby lizard": from the words "pareya" - cheek and "zauros" - lizard, lizard; the animal-toothed lizard of foreigners is named so in memory of the famous geologist - prof. A. A. Inostrantseva (1843-1919).

The richest finds from the ancient life of the Earth of the remains of these animals are associated with the name of the enthusiastic geologist prof. V.P. Amalitsky(1860-1917). This persistent researcher, without receiving the necessary support from the treasury, nevertheless achieved remarkable results in his work. Instead of a well-deserved summer vacation, he, together with his wife, who shared all the hardships with him, went in a boat with two oarsmen in search of the remnants of animal-like dinosaurs.

Stubbornly, for four years he conducted his research on the Sukhona, the Northern Dvina and other rivers. Finally, he managed to make discoveries extremely valuable for world science on the Northern Dvina, not far from the city of Kotlas.

Here, in the coastal cliff, the rivers were found in thick lentils of sand and sandstone, among striped junk, nodules of bones of ancient animals (nodules are stone accumulations). The fees of just one year of work of geologists took two freight cars during transportation.

Subsequent developments of these bone-bearing accumulations further enriched the information about the Permian reptiles.

Place of finds of the Permian lizards discovered by the professor V.P. Amalitsky in 1897, the right bank of the Malaya Severnaya Dvina River near the village of Efimovka, near the town of Kotlas.

The richest collections taken out from here are determined by tens of tons, and the skeletons collected from them represent the richest collection in the Paleontological Museum of the Academy of Sciences, which has no equal in any museum in the world.

Among the ancient animal-like Permian reptiles, the original three-meter predator Dimetrodon stood out, otherwise it was “two-dimensional” in length and height (from the ancient Greek words: “di” - twice and “metron” - measure).

Its characteristic feature is the unusually long processes of the vertebrae, forming a high crest on the animal's back (up to 80 centimeters), apparently, were connected by a skin membrane. In addition to predators, this group of reptiles also included plant- or mollusk-eating forms, also of very significant sizes. The fact that they ate molluscs can be judged by the structure of their teeth, suitable for crushing and grinding shells. (No ratings yet)